The proposed facility in this UAB Multipurpose Arthritis and Musculoskeletal disease Center (MAMDC) application provides for a valuable and dynamic set of resources reflecting the intensity and direction of research endeavors and efforts at The University of Alabama at Birmingham (UAB). The UAB Transgenic Animal/ES Cell Resource (Resource) provides state-of-the-art gene transfer technology including the production of both gain-of-function and/or loss-of-function ("knockout") mouse models. The Resource produces transgenic mice using both DNA microinjection and embryonic stem cell (ES cell) transfer methodologies. However, the costs for manipulation and transfer of embryonic stem cells is considerable greater than that for DNA microinjection, hence, the absolute costs preclude the utilization of this valuable modeling system. Currently, investigators interested in ES cell technology must establish in vitro ES cell techniques within their laboratory. Once cell lines are propagated, the PI is responsible not only for all preliminary in vitro testing but for the costs associated with in vivo testing of cell lines. Thus, the inherent initial costs effectively limit novel experimentation. The proposed core will provide a more comprehensive program for the development of ES cell-derived mouse models which will be useful to explore in vivo modulation of human gene expression and as a preclinical experimental model system. Therefore, the specific aim of this proposal is to reduce the developmental costs associated with ES cell culture and manipulation, leading to the production of pathogen-free mouse models for MAMDC investigators. This proposal will be used specifically to support: a) setup costs for a full-time ES cell culture program, b) cell transfection and culture, c) clone preparation for investigators, d) propagation of investigator identified cell clones for founder stem cell-derived or "knockout" mouse production, e) a repository for ES cell lines and investigator clones, f) evaluation and implementation of new technologies as they become relevant over the duration of the proposed program, and g) maintenance and testing of cell lines obtained from different investigators through to cell injection into mouse embryos, thereby characterizing the relative utility and efficiency associated with specific lines and cell passages.